THE GIANT SCALLOP (Pecten tenuicostatus, Mighels.) 



Most of the material upon which these observations were made 

 was secured near Bass Harbor, Mount Desert Island, Maine, 

 during the summer of 1901. Scallops in that region are fairly- 

 abundant but are now for the most part confined to water 40 

 fathoms or more in depth and are accordingly only to be 

 obtained by dredging. 



The scallop industry of Maine has undergone some changes 

 since the appearance of Smith's (28) paper in 1889, but on the 

 whole the changes are not very important. Some of the beds' 

 have run out so they are not profitable to work, and others have 

 been discovered. Most of the good beds are now in water of 

 from 40 to 60 fathoms and the scallops are somewhat smaller 

 than in former years but the methods of catching them do not 

 seem to have changed much. 



The majority of lamellibranchs are adapted for burrowing 

 more or less in mud or sand, are elongated, a shape that makes 

 burrowing easy, and are provided with two adductor muscles for 

 closing the shell, a desirable number for a shell and body of this 

 shape. Such animals usually move very slowly, by thrusting 

 the foot out into the mud, swelling its end to form an anchor, 

 and then drawing the shell with the inclosed body to the position 

 of the anchored foot. The shell may, or may not be capable of 

 closing tightly, this being dependent in part upon how deep the 

 animal burrows, and accordingly how well it is protected by the 

 overlying mud, and in part by other conditions. Such forms, 

 when disturbed, usually close the shell rather slowly and keep it 

 closed until probable danger is past. 



It is common for lamellibranchs that live in or about the 

 mud or s'and to make use of a current of water, which they 



